Physical immune escape: Weakened mechanical communication leads to escape of metastatic colorectal carcinoma cells from macrophages.

The significance of biochemical cues in the tumor immune microenvironment in affecting cancer metastasis is well established, but the role of physical factors in the microenvironment remains largely unexplored. In this article, we investigated how the mechanical interaction between cancer cells and immune cells, mediated by extracellular matrix (ECM), influences immune escape of cancer cells. We focus on the mechanical regulation of macrophages' targeting ability on two distinct types of colorectal carcinoma (CRC) cells with different metastatic potentials. Our results show that macrophages can effectively target CRC cells with low metastatic potential, due to the strong contraction exhibited by the cancer cells on the ECM, and that cancer cells with high metastatic potential demonstrated weakened contractions on the ECM and can thus evade macrophage attack to achieve immune escape. Our findings regarding the intricate mechanical interactions between immune cells and cancer cells can serve as a crucial reference for further exploration of cancer immunotherapy strategies.

Radiation-induced fibrosis: Mechanisms and therapeutic strategies from an immune microenvironment perspective.

Radiation-induced fibrosis (RIF) is a severe chronic complication of radiotherapy (RT) manifested by excessive extracellular matrix (ECM) components deposition within the irradiated area. The lung, heart, skin, jaw, pelvic organs and so on may be affected by RIF, which hampers body functions and quality of life. There is accumulating evidence suggesting that the immune microenvironment may play a key regulatory role in RIF. This article discussed the synergetic or antagonistic effects of immune cells and mediators in regulating RIF's development. Several potential preventative and therapeutic strategies for RIF were proposed based on the immunological mechanisms to provide clinicians with improved cognition and clinical treatment guidance.

Validation of an organ mapping antibody panel for cyclical immunofluorescence microscopy on normal human kidneys.

The lack of standardization in antibody validation remains a major contributor to irreproducibility of human research. To address this, we have applied a standardized approach to validate a panel of antibodies to identify 18 major cell types and 5 extracellular matrix compartments in the human kidney by immunofluorescence (IF) microscopy. We have used these to generate an organ mapping antibody panel for two-dimensional (2-D) and three-dimensional (3-D) cyclical IF (CyCIF) to provide a more detailed method for evaluating tissue segmentation and volumes using a larger panel of markers than would normally be possible using standard fluorescence microscopy. CyCIF also makes it possible to perform multiplexed IF microscopy of whole slide images, which is a distinct advantage over other multiplexed imaging technologies that are applicable to limited fields of view. This enables a broader view of cell distributions across larger anatomical regions, allowing a better chance to capture localized regions of dysfunction in diseased tissues. These methods are broadly accessible to any laboratory with a fluorescence microscope, enabling spatial cellular phenotyping in normal and disease states. We also provide a detailed solution for image alignment between CyCIF cycles that can be used by investigators to perform these studies without programming experience using open-sourced software. This ability to perform multiplexed imaging without specialized instrumentation or computational skills opens the door to integration with more highly dimensional molecular imaging modalities such as spatial transcriptomics and imaging mass spectrometry, enabling the discovery of molecular markers of specific cell types, and how these are altered in disease.NEW & NOTEWORTHY We describe here validation criteria used to define on organ mapping panel of antibodies that can be used to define 18 cell types and five extracellular matrix compartments using cyclical immunofluorescence (CyCIF) microscopy. As CyCIF does not require specialized instrumentation, and image registration required to assemble CyCIF images can be performed by any laboratory without specialized computational skills, this technology is accessible to any laboratory with access to a fluorescence microscope and digital scanner.

Mechanoimmunology in the solid tumor microenvironment.

The tumor microenvironment (TME) is a complex and dynamic ecosystem that adjoins the cancer cells within solid tumors and comprises distinct components such as extracellular matrix, stromal and immune cells, blood vessels, and an abundance of signaling molecules. In recent years, the mechanical properties of the TME have emerged as critical determinants of tumor progression and therapeutic response. Aberrant mechanical cues, including altered tissue architecture and stiffness, contribute to tumor progression, metastasis, and resistance to treatment. Moreover, burgeoning immunotherapies hold great promise for harnessing the immune system to target and eliminate solid malignancies; however, their success is hindered by the hostile mechanical landscape of the TME, which can impede immune cell infiltration, function, and persistence. Consequently, understanding TME mechanoimmunology - the interplay between mechanical forces and immune cell behavior - is essential for developing effective solid cancer therapies. Here, we review the role of TME mechanics in tumor immunology, focusing on recent therapeutic interventions aimed at modulating the mechanical properties of the TME to potentiate T cell immunotherapies, and innovative assays tailored to evaluate their clinical efficacy.

Granzymes in health and diseases: the good, the bad and the ugly.

Granzymes are a family of serine proteases, composed of five human members: GA, B, H, M and K. They were first discovered in the 1980s within cytotoxic granules released during NK cell- and T cell-mediated killing. Through their various proteolytic activities, granzymes can trigger different pathways within cells, all of which ultimately lead to the same result, cell death. Over the years, the initial consideration of granzymes as mere cytotoxic mediators has changed due to surprising findings demonstrating their expression in cells other than immune effectors as well as new intracellular and extracellular activities. Additional roles have been identified in the extracellular milieu, following granzyme escape from the immunological synapse or their release by specific cell types. Outside the cell, granzyme activities mediate extracellular matrix alteration via the degradation of matrix proteins or surface receptors. In certain contexts, these processes are essential for tissue homeostasis; in others, excessive matrix degradation and extensive cell death contribute to the onset of chronic diseases, inflammation, and autoimmunity. Here, we provide an overview of both the physiological and pathological roles of granzymes, highlighting their utility while also recognizing how their unregulated presence can trigger the development and/or worsening of diseases.

Nets in fibrosis: Bridging innate immunity and tissue remodeling.

Fibrosis, a complex pathological process characterized by excessive deposition of extracellular matrix components, leads to tissue scarring and dysfunction. Emerging evidence suggests that neutrophil extracellular traps (NETs), composed of DNA, histones, and antimicrobial proteins, significantly contribute to fibrotic diseases pathogenesis. This review summarizes the process of NETs production, molecular mechanisms, and related diseases, and outlines the cellular and molecular mechanisms associated with fibrosis. Subsequently, this review comprehensively summarizes the current understanding of the intricate interplay between NETs and fibrosis across various organs, including the lung, liver, kidney, skin, and heart. The mechanisms by which NETs contribute to fibrogenesis, including their ability to promote inflammation, induce epithelial-mesenchymal transition (EMT), activate fibroblasts, deposit extracellular matrix (ECM) components, and trigger TLR4 signaling were explored. This review aimed to provide insights into the complex relationship between NETs and fibrosis via a comprehensive analysis of existing reports, offering novel perspectives for future research and therapeutic interventions.

3D bioprinted tumor model: a prompt and convenient platform for overcoming immunotherapy resistance by recapitulating the tumor microenvironment.

BACKGROUND: Cancer immunotherapy is receiving worldwide attention for its induction of an anti-tumor response. However, it has had limited efficacy in some patients who acquired resistance. The dynamic and sophisticated complexity of the tumor microenvironment (TME) is the leading contributor to this clinical dilemma. Through recapitulating the physiological features of the TME, 3D bioprinting is a promising research tool for cancer immunotherapy, which preserves in vivo malignant aggressiveness, heterogeneity, and the cell-cell/matrix interactions. It has been reported that application of 3D bioprinting holds potential to address the challenges of immunotherapy resistance and facilitate personalized medication. CONCLUSIONS AND PERSPECTIVES: In this review, we briefly summarize the contributions of cellular and noncellular components of the TME in the development of immunotherapy resistance, and introduce recent advances in 3D bioprinted tumor models that served as platforms to study the interactions between tumor cells and the TME. By constructing multicellular 3D bioprinted tumor models, cellular and noncellular crosstalk is reproduced between tumor cells, immune cells, fibroblasts, adipocytes, and the extracellular matrix (ECM) within the TME. In the future, by quickly preparing 3D bioprinted tumor models with patient-derived components, information on tumor immunotherapy resistance can be obtained timely for clinical reference. The combined application with tumoroid or other 3D culture technologies will also help to better simulate the complexity and dynamics of tumor microenvironment in vitro. We aim to provide new perspectives for overcoming cancer immunotherapy resistance and inspire multidisciplinary research to improve the clinical application of 3D bioprinting technology.

More Velcro for the TGF-ß1 straitjacket: A new antibody straps latent TGF-ß1 to the matrix.

In this issue of Science Signaling, Jackson et al. present a new antibody strategy to-quite literally-strap transforming growth factor-ß1 (TGF-ß1) to latent complexes in the extracellular matrix. The antibody has no effect on latent TGF-ß1 presented on the surface of immune cells and thus allows targeting of the detrimental effects of TGF-ß1 in fibrosis without affecting its beneficial immune-suppressing activities.

The Tumor Immune Microenvironment plays a Key Role in Driving the Progression of Cholangiocarcinoma.

Cholangiocarcinoma (CCA) is an epithelial cancer distinguished by bile duct cell differentiation and is also a fibroproliferative tumor. It is characterized by a dense mesenchyme and a complex tumor immune microenvironment (TME). The TME comprises both cellular and non-cellular components. The celluar component includes CCA cells, immune cells and mesenchymal cells represented by the cancer-associated fibroblasts (CAFs), while the non-cellular component is represented by mesenchymal elements such as the extracellular matrix (ECM). Recent studies have demonstrated the important role of the TME in the development, progression, and treatment resistance of CCA. These cell-associated prognostic markers as well as intercellular connections, may serve as potential therapeutic targets and could inspire new treatment approaches for CCA in the future. This paper aims to summarize the current understanding of CCA's immune microenvironment, focusing on immune cells, mesenchymal cells, ECM, intercellular interactions, and metabolism within the microenvironment.

Crosstalk between T lymphocyte and extracellular matrix in tumor microenvironment.

The extracellular matrix (ECM) is a complex three-dimensional structure composed of proteins, glycans, and proteoglycans, constituting a critical component of the tumor microenvironment. Complex interactions among immune cells, extracellular matrix, and tumor cells promote tumor development and metastasis, consequently influencing therapeutic efficacy. Hence, elucidating these interaction mechanisms is pivotal for precision cancer therapy. T lymphocytes are an important component of the immune system, exerting direct anti-tumor effects by attacking tumor cells or releasing lymphokines to enhance immune effects. The ECM significantly influences T cells function and infiltration within the tumor microenvironment, thereby impacting the behavior and biological characteristics of tumor cells. T cells are involved in regulating the synthesis, degradation, and remodeling of the extracellular matrix through the secretion of cytokines and enzymes. As a result, it affects the proliferation and invasive ability of tumor cells as well as the efficacy of immunotherapy. This review discusses the mechanisms underlying T lymphocyte-ECM interactions in the tumor immune microenvironment and their potential application in immunotherapy. It provides novel insights for the development of innovative tumor therapeutic strategies and drug.

Oncogene-induced matrix reorganization controls CD8+ T cell function in the soft-tissue sarcoma microenvironment.

CD8+ T cell dysfunction impedes antitumor immunity in solid cancers, but the underlying mechanisms are diverse and poorly understood. Extracellular matrix (ECM) composition has been linked to impaired T cell migration and enhanced tumor progression; however, impacts of individual ECM molecules on T cell function in the tumor microenvironment (TME) are only beginning to be elucidated. Upstream regulators of aberrant ECM deposition and organization in solid tumors are equally ill-defined. Therefore, we investigated how ECM composition modulates CD8+ T cell function in undifferentiated pleomorphic sarcoma (UPS), an immunologically active desmoplastic tumor. Using an autochthonous murine model of UPS and data from multiple human patient cohorts, we discovered a multifaceted mechanism wherein the transcriptional coactivator YAP1 promotes collagen VI (COLVI) deposition in the UPS TME. In turn, COLVI induces CD8+ T cell dysfunction and immune evasion by remodeling fibrillar collagen and inhibiting T cell autophagic flux. Unexpectedly, collagen I (COLI) opposed COLVI in this setting, promoting CD8+ T cell function and acting as a tumor suppressor. Thus, CD8+ T cell responses in sarcoma depend on oncogene-mediated ECM composition and remodeling.

Remodelamento da matriz extracelular em degeneração experimental do disco intervertebral / Extracellular matrix remodeling in experimental intervertebral disc degeneration

Objetivo: Avaliar a remodelação da matriz extracelular na degeneração do disco intervertebral através do modelo experimental degeneração do disco intervertebral. Métodos: o modelo de indução da degeneração discal, utilizando agulha 20G e rotação de 360º, foi aplicado por 30 segundos entre a sexta/sétima e oitava / nona vértebras coccígeas de ratos machos da linhagem Wistar. O nível intermediário, entre a sétima e oitava vértebras, foi tomado como controle, não sendo submetido à punção. A distribuição de constituintes da matriz extracelular envolvidos com mecanismos de remodelamento e inflamação, como proteoglicanos (agrecam, decorim, biglicam), fatores de crescimento (TGFβ), isoformas de heparanase (HPSE1, HPSE2), metaloprotease-9 (MMP9) e interleucinas (IL-6, IL-10) foram avaliadas no período pós-lesão (15 e 30 dias) e no grupo controle (discos coletados imediatamente após a punção, dia zero). No 15 o dia, fase aguda da doença, notou-se redução da expressão dos constituintes da matriz extracelular, porém não houve diferenças na expressão de interleucinas. Aos 30 dias, as moléculas seguiram um padrão de expressão muito similar ao grupo controle (não acometido por degeneração discal). Resultados: os resultados mostram que na fase aguda ocorrem alterações significativas na matriz extracelular e, na fase tardia, o disco intervertebral retorna a um perfil semelhante ao tecido não acometido por degeneração, provavelmente devido a um intenso processo de remodelamento da matriz extracelular que é capaz de regenerar o tecido lesionado. Conclusão: o modelo experimental utilizado demonstrou a ocorrência de alterações significativas da matriz extracelular durante o período analisado após a indução da degeneração do disco intervertebral. Trabalho experimental.

Objective: To evaluate the remodeling of the extracellular matrix in intervertebral disc degeneration through the experimental model of intervertebral disc degeneration. Methods: The model of disk degeneration induction, using needle 20G and 360º rotation, was applied for 30 seconds between the 6th/7th , and 8th/9th coccygeal vertebrae of Wistar rats. The intermediary level, between th e 7th and 8th vertebrae, was taken as control, not being subjected puncture. The distribution of the extracellular matrix components involved in the remodeling and inflammation process, such as proteoglycans (aggrecan, decorin, biglycan), growth factors (TGFβ), heparanase isoforms (HPSE1, HPSE2), metaloprotesasis-9 (MMP9) and interleukins (IL-6, IL-10) was analyzed during the pos-injury period (15 to 30 days) and in the control group (discs collected immediately after the puncture, day zero). On the 15th day, acute phase of the disease, a reduced expression of extracellular matrix components had been observed, whilst there were no differences in the interleukins expression. At 30 days, the molecules followed a very similar pattern of expression in the control group (not affected by disc degeneration). Results: the results show that during the acute phase significant alterations in the extracellular matrix components occur and in the late phase intervertebral disc returns to a profile similar to noninvolved tissue, probably due to extensive remodeling process of the extracellular matrix that is capable of regenerating the damaged tissue. Conclusion: the experimental model used demonstrated the occurrence of significant changes in the extracellular matrix during the period analyzed after induction of intervertebral disc degeneration. Laboratory investigation.

Imunofenotipagem e remodelamento da matriz extracelular na sarcoidose pulmonar e extrapulmonar / Immunophenotyping and extracellular matrix remodeling in pulmonary and extrapulmonary sarcoidosis

OBJETIVO: Investigar o significado de marcadores de imunidade celular e de componentes elásticos/colágeno da matriz extracelular em estruturas granulomatosas em biópsias de pacientes com sarcoidose pulmonar ou extrapulmonar. MÉTODOS: Determinações qualitativas e quantitativas de células inflamatórias, de fibras de colágeno e de fibras elásticas em estruturas granulomatosas em biópsias cirúrgicas de 40 pacientes com sarcoidose pulmonar e extrapulmonar foram realizadas por histomorfometria, imuno-histoquímica, e técnicas de coloração com picrosirius e resorcina-fucsina de Weigert. RESULTADOS: A densidade de linfócitos, macrófagos e neutrófilos nas biópsias extrapulmonares foi significativamente maior do que nas biópsias pulmonares. Os granulomas pulmonares apresentaram uma quantidade significativamente maior de fibras de colágeno e menor densidade de fibras elásticas que os granulomas extrapulmonares. A quantidade de macrófagos nos granulomas pulmonares correlacionou-se com CVF (p < 0,05), ao passo que as quantidades de linfócitos CD3+, CD4+ e CD8+ correlacionaram-se com a relação VEF1/CVF e com CV. Houve correlações negativas entre CPT e contagem de células CD1a+ (p < 0,05) e entre DLCO e densidade de fibras colágenas/elásticas (r = -0,90; p = 0,04). CONCLUSÕES: A imunofenotipagem e o remodelamento apresentaram características diferentes nas biópsias dos pacientes com sarcoidose pulmonar e extrapulmonar. Essas diferenças correlacionaram-se com os dados clínicos e espirométricos dos pacientes, sugerindo que há duas vias envolvidas no mecanismo de depuração de antígenos, que foi mais eficaz nos pulmões e linfonodos.

OBJECTIVE: To investigate the significance of cellular immune markers, as well as that of collagen and elastic components of the extracellular matrix, within granulomatous structures in biopsies of patients with pulmonary or extrapulmonary sarcoidosis. METHODS: We carried out qualitative and quantitative evaluations of inflammatory cells, collagen fibers, and elastic fibers in granulomatous structures in surgical biopsies of 40 patients with pulmonary and extrapulmonary sarcoidosis using histomorphometry, immunohistochemistry, picrosirius red staining, and Weigert's resorcin-fuchsin staining. RESULTS: The extrapulmonary tissue biopsies presented significantly higher densities of lymphocytes, macrophages, and neutrophils than did the lung tissue biopsies. Pulmonary granulomas showed a significantly higher number of collagen fibers and a lower density of elastic fibers than did extrapulmonary granulomas. The amount of macrophages in the lung samples correlated with FVC (p < 0.05), whereas the amount of CD3+, CD4+, and CD8+ lymphocytes correlated with the FEV1/FVC ratio and VC. There were inverse correlations between TLC and the CD1a+ cell count (p < 0.05), as well as between DLCO and collagen/elastic fiber density (r = -0.90; p = 0.04). CONCLUSIONS: Immunophenotyping and remodeling both showed differences between pulmonary and extrapulmonary sarcoidosis in terms of the characteristics of the biopsy samples. These differences correlated with the clinical and spirometric data obtained for the patients, suggesting that two different pathways are involved in the mechanism of antigen clearance, which was more effective in the lungs and lymph nodes.

Trampas extracelulares de neutrófilos: un mecanismo de defensa con dos caras / Neutrophil extracellular traps: a 2-faced host defense mechanism

Los neutrófilos desempeñan un papel clave en el sistema inmune innato, constituyendo la primera línea de defensa del organismo. Recientemente se ha demostrado que además de eliminar patógenos mediante fagocitosis o secreción de antimicrobianos, los neutrófilos pueden capturar y matar microorganismos a través de la producción de estructuras extracelulares compuestas de ADN y proteínas antimicrobianas denominadas neutrophil extracellular traps (NETs, «trampas extracelulares de neutrófilos»). Si bien cantidades fisiológicas de NETs resultan importantes como agentes antiinfecciosos, valores altos en circulación pueden resultar en una situación fisiopatológica opuesta a la buscada, generando, por ejemplo, daño tisular. Por otro lado, la excesiva formación de NETs o alteraciones en su remoción se encontrarían asociadas al desarrollo de ciertas enfermedades autoinmunes. Esta revisión describe la estructura, función y generación de las NETs, y su posible implicancia en la iniciación y/o en el desarrollo de diversas enfermedades (AU)

Neutrophils play a key role in the innate immune system, providing the first line of host defense. In addition to their ability to eliminate pathogens by phagocytosis and antimicrobial secretions, it has recently been shown that neutrophils can trap and kill microorganisms by the release of extracellular structures composed of DNA and antimicrobial proteins called neutrophil extracellular traps (NETs). Although physiological amounts of NETs are important as antimicrobial agents, high levels of NETs in circulation may result in severe tissue damage. Besides, the excessive generation of NETs or a disruption in their clearance mechanism might be associated with the development of certain autoimmune diseases. This review describes the structure, function and generation of NETs, and their possible implication in the initiation and/or progression of different diseases (AU)

La matriz extracelular: morfología, función y biotensegridad (parte I) / Extracellular matrix: morphology, function and biotensegrity (part I)

La matriz extracelular (MEC) representa una red tridimensionalque engloba todos los órganos, tejidos y células delorganismo. Constituye un filtro biofísico de protección, nutricióne inervación celular y el terreno para la respuesta inmune,angiogénesis, fibrosis y regeneración tisular. Y representael medio de transmisión de fuerzas mecánicas a la membranabasal, que a través de las integrinas soporta el sistema de tensegridady activa los mecanismos epigenéticos celulares. Laalteración de la MEC supone la pérdida de su función de filtroeficaz, nutrición, eliminación, denervación celular, pérdidade la capacidad de regeneración y cicatrización y alteración dela transmisión mecánica o mecanotransducción. También lapérdida del sustrato para una correcta respuesta inmune anteagentes infecciosos, tumorales y tóxicos.Los tumores son tejidos funcionales conectados y dependientesdel microambiente. El microambiente tumoral, constituidopor la MEC, células del estroma y la propia respuestainmune, son determinantes de la morfología y clasificacióntumoral, agresividad clínica, pronóstico y respuesta altratamiento del tumor. Tanto en condiciones fisiológicascomo patológicas, la comunicación recíproca entre célulasdel estroma y el parénquima dirige la expresión génica. Lacapacidad oncogénica del estroma procede tanto de losfibroblastos asociados al tumor como de la celularidad de larespuesta inmune y la alteración de la tensegridad por laMEC. La transición epitelio-mesenquimal es el cambio quetransforma una célula normal o «benigna» en «maligna». Elcitoesqueleto pseudomesenquimal otorga las propiedades demigración, invasión y diseminación. Y viceversa, el fenotipomaligno es reversible a través de la corrección de las clavesque facilita el microambiente tumoral(AU)

Extracellular matrix (ECM) is a three-dimensional networkthat envelopes all the organs, tissues and cells of thebody. A biophysical filter that provides protection, nutritionand cell innervation, it is the site for immune response,angiogenesis, fibrosis and tissue regeneration. It is also thetransport medium for mechanical forces to the basal membranethrough integrins that support the tensegrity system,activating cellular epigenetic mechanisms. The disruptionof the ECM leads to a functional loss of nutrition, elimination,cell innervation, regenerative capacity and wound healingas well as alterations in mechanical transduction. Thisloss also disrupts the immune response to pathogens,tumour cells and toxins.Tumours are functionally connected tissues whichdepend on the microenvironment. This tumour microenvironment,made up of ECM, stromal cells and the immuneresponse, determines the morphology and tumour histopathologicalclassification, clinical behaviour, prognosis andimmune response to the tumour. Both in physiological andpathological conditions, reciprocity in the communicationbetween stromal and parenchymal cells determine geneexpression. The oncogenic capacity of the stroma dependson tumour associated fibroblasts, immune system cellularityand disruption of tensegrity by ECM. Epithelialmesenchymaltransition is the change that transforms a normalor benign cell into a malignant cell. The «pseudo-mensenchymal» cytoskeleton is responsible for migration,invasion and dissemination, and vice-versa, the malignantphenotype is reversible through the correction of the microenvironmentalfactors that favour tumour growth(AU)

Expresión de la lisil oxidasa (LOX) en la pared vascular: mecanismos implicados en la regulación de la LOX por lipoproteínas de baja densidad / Lysyl oxidase (LOX) expression in the vascular wall: mechanisms involved in LOX regulation by low density lipoproteins

Introducción. La lisil oxidasa (LOX) es una enzima implicada en la estabilización de la matriz extracelular que podría ser clave en la disfunción endotelial desencadenada por factores de riesgo aterosclerótico. Hemos analizado el patrón de expresión de las enzimas de la familia de LOX en la pared vascular y determinado los mecanismos implicados en la modulación de esta enzima por lipoproteínas de baja densidad (LDL) en células vasculares. Material y métodos. La expresión de la LOX y de otras enzimas de la familia se analizó en arterias coronarias humanas, aorta abdominal porcina, células endoteliales de aorta porcina (PAEC) y células musculares lisas (CML), mediante inmunohistoquímica, RT-PCR y/o Northern-blot. Resultados. Hemos observado grandes diferencias en el patrón de expresión de las enzimas de la familia de la LOX en la pared vascular. La LOX se expresa preferentemente en el endotelio y en la adventicia de arterias coronarias humanas y de aorta porcina. El tratamiento con LDL disminuye la expresión de esta enzima en PAEC y CML en cultivo. Este efecto se produce por un mecanismo transcripcional, sin que se vea afectada la estabilidad del mensajero. La esfingosina-1-fosfato (S1P), componente bioactivo de las LDL, no modificó la expresión de la LOX, y la inhibición de proteínas G sensibles a toxina pertúsica no revertió el efecto de las lipoproteínas. Sin embargo, observamos que la inhibición del procesamiento lisosomal con cloroquina previno la disminución de la expresión de la LOX causada por las LDL. Conclusiones. La disminución de la expresión de la LOX por LDL requiere el procesamiento lisosomal de la lipoproteína. La regulación de esta enzima por lipoproteínas y su fuerte expresión en el endotelio vascular apoyan el papel de la LOX en la disfunción endotelial desencadenada por la hipercolesterolemia y sugieren su contribución en el proceso aterosclerótico (AU)

Introduction. Lysyl oxidase (LOX) is an enzyme involved in extracellular matrix stabilization that could play a key role in endothelial dysfunction triggered by atherosclerotic risk factors. We analyzed the expression pattern of LOX isoenzymes in the vascular wall and determined the molecular mechanisms involved in low density lipoproteins (LDL)-mediated LOX modulation in vascular cells. Material and methods. LOX isoenzyme expression was analyzed in human coronary arteries, porcine abdominal aorta, porcine aortic endothelial cells (PAEC) and vascular smooth muscle cells (VSMC) by immunohistochemistry, RT-PCR and/or Northern-blot. Results. We observed marked differences in the vascular expression pattern of LOX isoenzymes. LOX was preferentially expressed in endothelium and adventitia in human coronary arteries and in porcine abdominal aorta. LDL decreased LOX expression in both PAEC and VSMC in culture. This effect was due to a transcription mechanism that did not seem to alter mRNA stability. Sphingosine-1-phosphate (S1P), an LDL bioactive component, did not modify LOX expression, and inhibition of pertussis toxin-sensitive G-proteins did not prevent the effect of lipoproteins. Finally, we observed that inhibition of lysosomal processing with chloroquine abolished the LDL-induced LOX downregulation. Conclusions. LOX downregulation by LDL requires lipoprotein lysosomal processing. Both LOX regulation by lipoproteins and its strong endothelial expression support the role of this enzyme in endothelial dysfunction triggered by hypercholesterolemia and suggest that it contributes to the atherosclerotic process (AU)

Autoantibodies as tools for biochemists and cell biologists

In this report we deal with the interesting repertoire of autoantigens and discuss that they represent functional and evolutionary conserved sites in proteins. In addition, we show that the autoantibodies spontaneously generated against these antoantigens can be useful tools in the study of important cellular phenomena.

Intrinsic and extrinsic circuits controling the thymic microenvironment

The thymic microenvironment plays a key role in the general process of intrathymic T cell differentiation, that ultimately yields the vast majority of the T cell repertoire. This nonlymphoid compartment is mostly composed of thymic epithelial cells (TEC), that together with dendritic cells, macrophages and elements of the extracellular matrix form a tridimensional network in which context thymocyte differentiation occurs. Microenvironmental cells modulate intrathymic T cell diferentiation by means of a variety of secretory products, comprising several cytokines and thymic hormones, as well as cell-cell interactions, including those mediated by MHC products, adhesion molecules and extracellular matrix ligands and receptors. When studying the physiology of the thymic microenvironment one should take into account the existence of intrinsic and extrinsic circuits controlling it. For example, we showed that interferon-gamma (IFN-gamma), a thymocyte-derived cytokine, is able to pleiotropically modulate both epithelial and dendritic cells of the thymus. Besides enhancing the expression of MHC class two molecules on these cell types, IFN-gamma regulates, in a dose-dependent biphasic manner, the expression of extracellular matrix ligands and receptors that implies a corresponding modulation on the ability of thymocytes to adhere onto IFN-gamma-treated TEC cultures. In addition, extrinsic endogenous circuits appear to continuously influence the thymic microenvironment. We evidenced that steroid, thyroid and pituitary hormones can modulate several aspects of TEC physiology including thymic hormone secretion, cytokeratin expression, cell growth as well as expression of extracellular matrix ligands and receptors. Latter effects directly intervene, at least as assessed by in vitro models, in TEC/thymocyte interactions. Other endogenous situations such as aging and autoimmunity also influence the thymic microenvironment. For example, in both conditions we showed a decay in thymic hormone secretion, changes in the expression of cortical and medullary cytokeratins, and an increase in extracellular matrix. Furthermore, the thymic microenvironment is modulated by stimuli from the environmental world such as infectious agents. In the Trypanosoma cruzi model, we noticed that both TEC and thymic macrophages are infected in vivo and in vitro...